1. Field of the Invention
The present invention relates to a compact cartridge changer capable of automatically changing, within a limited space, a plurality of cartridges of recording medium (e.g., magnetic tapes, etc.) disposed on an opposing rack, further relates to a data storage unit using such changer and including additional support components (e.g., a player, amplifiers, etc.), and still further, relates to an apparatus (e.g., computer, VTR, etc.) using such data storage unit.
2. Description of Related Art
A magnetic tape drive of a cartridge change type is capable of automatically changing a fully recorded cartridge tape for an empty cartridge tape by a cartridge changer when a quantity of data to be accessed and/or recorded is too large with respect to a single cartridge tape. FIG. 13 shows such a possible cartridge changer 1 having a recording-and-reproducing tape drive 2 disposed therein, and a rack unit 3 for storing cartridges is disposed above the recording-and-reproducing tape drive. A cartridge conveying unit 5 for extracting and conveying a cartridge is disposed in front of (i.e., to face a cartridge input port of) the recording-and-reproducing tape drive and the rack unit, such cartridge conveying unit 5 being constructed to convey a selected cartridge (e.g., 4a, 4b) between the rack unit and the recording-and-reproducing tape drive 2, i.e., convey in a vertical direction V and a horizontal direction H.
The rack unit 3 has a first rack 3a disposed opposite to the cartridge conveying unit 5 and containing cartridges 4a, and a second rack 3b disposed behind the first rack and containing cartridges 4b, i.e., such configuration represents opposing racks. The arrangement of the rack unit 3, having first and second racks 3a, 3b and cartridges stored therein is hereinafter called a "rack system". Since the cartridge conveying unit 5 is able to take out a cartridge only from a rack disposed opposite thereto (i.e., facing) the cartridge conveying unit, the rack unit 3 must be able to rotate R the first and second rack 3a, 3b through an angle of 180.degree. about a turning axis 13 substantially corresponding to the center of the rack unit, in order to allow access to and extraction/insertion of a cartridge 4b from the second rack. FIGS. 14a-14d are schematic plan views of the cartridge changer. The cartridge changer carries out operations illustrated in FIGS. 14a-14d to shift the first rack 3a from a front position opposite the cartridge conveying unit to a back position, and to shift the second rack 3b from the back position to the front position, to enable the cartridge conveying unit 5 to gain access to and extract/insert a cartridge from the second rack.
With respect to the turning operation of FIGS. 14a-14d, it is noted that typically there are limitations on an amount of space which is available to effect a turning operation of the rack in order to avoid contacting interference between parts of the turning rack system and other physical obstruction (e.g., walls or other objects). More particularly, within FIGS. 14a-14d, there is illustrated a constraint perimeter 50 representing an area within which the turning operation must be effected. For example, constraint perimeter 50 may be defined by the enclosed casing walls of a cartridge changer 1 (FIGS. 14a-14d) or data storage unit 102 (FIG. 16), or may be defined by other walls or other physical obstructions if a cartridge changer or data storage unit does not have an enclosed casing and is installed within an apparatus (100; FIG. 16), e.g., if a data storage unit 102 without an enclosed casing is installed within a drive bay 101 of a computer 100, the drive bay walls may define the clearance perimeter 50. Other types of physical objects may also represent obstructions.
Related to this discussion is also a turning periphery 60 as illustrated in FIGS. 14a-14d. More particularly, within such Figs. there is a turning periphery 60 representing the extent or path of an outermost portion (defined by a maximum distance across, width or diameter 70) of the rack system, as such rack system is rotated R about the turning axis 13. It can clearly be seen that the turning periphery 60 is within the clearance perimeter 50, and thus there is no interference problem associated with a turning of the rack system in FIGS. 14a-14d. Accordingly, from the above discussions and associated illustrations, it can be seen that a clearance of a clearance perimeter 50 must be greater than a turning periphery 60 defined by rotating a maximum width or diameter 70 of the rack system, in order to be able to rotate R the rack unit without special accommodations.
Discussion now turns to a mathematical analysis of the above discussion, and also discussion as to a disadvantaged arrangement having interference with obstructions. More particularly, suppose that in FIG. 15c each of the cartridges stored in the racks (not illustrated in FIG. 15c) have a width h and a depth b, and that a maximum width or diameter 70 of a most outwardly extending portion across the rack system (and through the turning axis 13) is defined as having a width "m". In FIG. 15c, illustrated minimum available or necessary distances from the center axis 13 of the cartridge changer to the closest inner surfaces of clearance periphery 50 (e.g., the opposite side panels) of the casing of the cartridge conveying unit are B+B', which (in the FIG. 15c illustration) are greater than both the width h and the maximum width m. In a rectangular rack system arrangement such as that shown in FIG. 15c and FIGS. 14a-14d, when the rack system is turned, the distance B+B' which is adequate for non-interference with the clearance perimeter 50, and which is related to the width h and depth b, is expressed by the expression: ##EQU1##
Stated more generally, if a maximum distance (e.g., diameter) m extending through the turning axis 13 and across the most widely extending portions (e.g., diagonal) of the rack system is defined as line 70 (FIGS. 15a-15c) having a dimension "m", then in order to be a non-interfering arrangement: EQU B+B'&gt;m (1b)
If this width is not available, the edges of the cartridge will collide with obstructions defining the clearance perimeter 50 (e.g., the side panels of the casing of the cartridge changer) and the rack unit is unable to turn as illustrated in FIGS. 15b.
Accordingly, if a limited space (i.e., clearance perimeter 50) exists for a cartridge changer arrangement where B+B'&lt;m, an opposing rack system cannot be turned within the clearance perimeter 50.